Sunday, April 14, 1935, began as a warm spring day in the western part of Oklahoma known as the Panhandle. The sun shone, birds sang, and a gentle southwest wind stirred the fields. In the small town of Guymon and in others like it, where most people were Protestant and went to church, people fanned themselves while ministers led them in prayers for rain. Severe drought— residents called it "drouth"—had plagued the Great Plains for five years, and crops were badly in need of moisture. "Good rains within three weeks mean a harvest," declared Reverend R.L. Wells at the Methodist Episcopal Church. "God rules all and our last resort is prayer."

When services ended, people flocked outside, ready to take advantage of the good weather. Some went on picnics. Others visited neighbors or went home to plant their gardens. Before the afternoon was over...